Electric motor



oct. 13,1925. 1,557,158

H. C. GRANT ELECTRIC IOTOR Filld lay 5. 1922 uf an Patented Oct. 13, 1925.

UNITED STATES PATENT OFFICE.

HARRY C. GRANT, 0F BAYONNE, NEW JERSEY, ASSIGNOR T0 KLAXON COMPANY, A

CORPORATION OF DELAWARE.

ELECTRIC MOTOR.

Application led Hay 3, 1922.

To all whom t may concern:

Be it known that I, HARRY C. GRANT, a citizen of the United States, and resident of Bayonne, in the county of Essex and State of New Jersey, have invented certam new and useful Improvements in Electric Motors, of which the following is a speciication.

My present invention is particularly designed for use in connection with the motor construction invented by Duncan A. McConnell and set forth in his application, Serial N0. 558,108 filed May 3, 1922.

lVhile certain details of my invention are adapted for use in other relations, it primarily concerns pole pieces and shoes for use in combination with the shell and bridge piece magnetic field circuit in such a motor. The nature and objects of the invention will be more fully understood from the following description in connection with the accomA panying drawings, in which- Fig. 1 is a side elevation with the casing broken away to show the operating parts of the instrument.

Fig. 2 is a section on the line 22, F ig. 1.

Figure 3 is a plan view of one of the pole pieces with the core riveted to it.

Referring to these drawings, the pro]ector 1 is secured to front casing 2 by flange 3 and rib 4, and also by soldering or brazing, if desired. The rear casing is an integral drawn shell 01 cup comprising a cylindrical portion 5, rear end wall 6, and preferably also, the diaphragm clamping ange 7 1s integral. The diaphragm 8 is secured between the clamping members by screws 9, preferably passing loosely through the front casing 2 and secured by nuts 10 which may be held from unscrewing by spring locking washers 1l of any known or desired type.

The rear wall 6 has a punched and drawn cylindrical extension 13 which constitutes a housing for the bearing 14 which may be threaded therein and secured by lock nut 15.

The shell 5, 6, is of iron or mild steel of such quality that itis capable of being punched and drawn to the shape shown 1n the drawings and also capable of being utilized as the magnetic circuit between the pole pieces of the motor. The pole pieces are preferably located near the rear wall of the cup and there is a bridge plece 31 across the cup near the open end thereof forming the front bearing for the armature shaft and Serial' No. 558,164.

this bridge piece is preferably of magnetic material forming part of the magnetic circuit of the motor field.

The peripheral wall is flattened in to form an inwardly projecting boss 1S with a fiat top 19 forming a good seat for the core pieces 2() and a flaring base as at 21. The outward flaring curvature of the boss away from the base of the core piece seems to make the metal cup more nearly a magnetic unit with the cores, affording somewhat easier and natural lines of flow of the magnetic energy.

The electrolnagnets have soft iron cores 20, each having a reduced shank 23, whereby it is riveted into extremely intimate engagement with the surface 19 of one of the shell bosses. The inner ends of cores 20 have square shoulders 50 of ample area and re duced shanks 51 which are riveted through the shoes or pole pieces 52. It is highly important that the engagement of the cores with the pole pieces at 50 be very intimate. Hence important features of my invention are making the core engaging surface of the pole pieces true planes and also making the corresponding inner surface 53 an approximate plane, with a counter sink 54, in which shank 51 can be powerfully and accurately riveted.

F or this and other reasons I form the pole piece 52 from very heavy rolled metal, say ji, inch in thickness, bent to approximate the correct curvature to suit the armature and with minimum, uniform clearance for the air gap of the magnetic circuit. A punching die and matrix are employed to punch the perforation for shank 51, to form the counter sink at 54, and to partially expel the edges of a wash-like portion 55, preferably simultaneously.

The pressure necessary for this purpose forms a perfectly true plane surface at 50 and a similar surface at 53, both of these surfaces extending symmetrically on opposite sides of a radius from the center of curvature of the pole piece. Furthermore by preference is a plane approximately tangent to the inner face of the shoe 52, while 5() is approximately tangent to the outer face thereof.

In practice the shoe 52 may be first riveted to the core 2O as at 54. Then the assembled cores and pole pieces may have the magnetizing coils mounted thereon and the Shanks 23 inserted through the `boss openings at 19. A mandrel having afor- Ward end of the exact internal diameter 13, and an intermediate ortion of the exact diameter required for t e fieldofthe motor, and having means at the rear for centering for the exact diameter of the interior of shell 5, may then be inserted. Its axis will, of course, be exactly centered on what is to be the axis of the armature shaft.

The riveting operation is then performed preferably by die presses acting simultaneously on both pole pieces so as to apply a balanced thrust through the cores upon the intervening mandrel. The pressures required for riveting are suliioient lto set the metal of the case and of the pole pieces to the diameter of the mandrel with great accuracy. Thus the magnetic field is centered and sized with great accuracy, permitting minimum clearance and small air gap between field and armature.

The motor armature 27, commutator 28, and shaft 29, may be of the usual construction. The rear end of shaft 29 rests in the bearing 14. The forward bearing for shaft 29 is in a transverse member, preferably of magnetic material, which may be either a Wall or merely a bridge piece 31, extending diametrically across the cup and secured in sition by screws 32, screwing down on ook washers 33.

This bridge Apiece 3:1 carries the brush holders 34 which consist of blocks of .insulatmg material, such as condensite or bakelite molded to shape 4under heat and preure, but these do not .concern my present invention.

While the diaphragm wear .piece does not concern my present invention, I may explain that it consists of a circular dam ing a an eccentric portion `projecting rom one side thereof and formed with a wear piece comprising an incline lemdin up to a more or less pronounced tip or 1i gn which extends substantially radial to the :axis of the wear piece, opposite bo and parallel with the cam .pr 'ections on the`rotor 40. The natur is qa erably in the form of a hard steel cup as Shown, and is secured in position by a stud screw 41.

The weairpieeeisseeuredbyanintegral shank 42 which is riveted through a :square aperture 413 4in the center of the diaphragm, throughs clmhiun washer 4A which is prefarably made of the same steel as the dia,- phrag'm, and thmugh a front washer 45. The diaphragm is cushioned from ntact with the metal clamping members by elastic washers 12, 12, preferably of cork composition.

I claim:

1. In a dynamo electric machine, a field for the armature comprising a drawn metal cup and, riveted Ito the peripheral walls 'ment `with a wall of the cu at one en thereof, interiorly pro' tin core s of softiron, each core pieehavging a body portion formed at the ends with ample-area abutment surfaces and, centrall projecti from each said surface, a reduced sh T0 riveting said surfaces into intimate en ag an at the other end to a fiel shoe, said shoe consisting of anylindrical segment of approximately uniform thickness punched and I5 shaped to form a perforation and an exte'. rior surface for engllgement with said abuty ment surface of t e core piece, approxi. mately tangent to the exterior surface of the' shoe. M 2. In a -dynamo electric machine, a field. for the armature comprising afdrawnI .41 cup and, riveted to the peripheral f thereof, interiorly projeetmcm-e nti-M soft iron, each core piece aving a body, portion formed at the ends with amplefamawmi. abutment surfaces and, centrally projecting?" 1 from each said surface, a. reduced shank riva; eting said surfaces intn .intimate 3^- ment with a wall of the cu at one en and QI at the other end to a shoe, said sheet?" consisting of a c .lindricalsegment punched and shaped to orm a perforation and anyA exterior surface Afor ent with abutment surface of the come piece, and an 05 interior surface for theliveti o 3. In a dynamo electric ma im, a field for the armature comprising. drawn metal cup and, riveted to the .peripheral walls: thereof, interiorly projecting core pieces of 123 soft iron,.eac`h core piece having a body portion formed at the ends with ample-area, abutment surfaces and, centrally from each said surface. a reduced 4shank r'rv etingsaid surfaces into intimate enga n nti` 105 with a wall ofthe cup at mefend: c at then other end to a field shoe, said shoe consist-F ing of a cylindrical segment of approximate- Y" 1y unifonm thickness punched and shaped.2

to form a :perforation and an exterior sur-:

face for engagement withisaid abutment face of .the core piene, approximately gent to the lanterior surface orf the shoe, md5 an interina surface for the rivet appmr! mately to the inner face.v the 4. Imadynamo electric machines the armature comprng a alr'amn metal cn and, riveted to the peripheral walls th i interiorly projecting core pieces of soft each core piece having a body l formed atfthe end with .am area ment sur aces an oen y projec from each said surface, a reduced shanktlh'lgf' eting said surfaces into intimate eng with a wall of the cupmt one end un Mtl. W5 other lend to 1a field alma, said shoe consi ing of `a cylindrical ont punched sha to form a pe Gratien and an tenor surface for engagement with snif abutment surface of the r piece, .and am l.

interior surface for the riveting, said inner surface face being counter sunk concentrically with the perforation to afford a heading recess for the shank.

5. In a dynamo electric machine, a field for the armature comprising a drawn metal cup and, riveted to the peripheral walls thereof, interiorly projecting core pieces of soft iron, each core piece having a body portion formed at the ends With ample-area abutment surfaces and, centrally projecting from each said surface, a reduced shank riveting said surfaces into intimate engagement With a Wall of the cup at one end and at the other end to a field shoe, said shoe consisting of a cylindrical segment punched to form a partially extruded Washer-like portion.

6. In a dynamo electric machine, a field for the armature comprising a drawn metal cup and, riveted to the peripheral Walls thereof, interiorly projecting core pieces of soft iron, each core piece having a body portion formed at the ends with ample-area abutment surfaces and, centrally projecting from each said surface, a reduced shank riveting said surfaces into intimate engagement With a Wall of the cup at one end and at the other end to a field shoe, said shoe consisting of a cylindrical segment punched to form a partially extruded washer-like portion of substantially the same thickness as the material of the shoe, the surfaces of which are approximately tangential to the exterior and interior curved surfaces of the shoe.

7. A shoe for the field of a dynamo electric machine, consisting of heavy rolled sheet metal formed to the curvature of the armature and having a perforation through which a core piece may be riveted and partially extruded around said perforation to form a Washer-like projection affording approximately parallel flat outer and inner surfaces for the riveting.

8. A shoe for the field of a dynamo electric machine, consisting of heavy rolled sheet metal formed to the curvature of the armature and having a perforation through which a core piece may be riveted and partially extruded around said perforation to form a Washer-like projection of a thickness approximately equal to the thickness of the shoe.

9. A shoe for the field of a dynamo electric machine, consisting of heavy rolled sheet metal formed to the curvature of the armature and having a perforation through which a core piece may be riveted and partially extruded around said perforation to form a Washer-like projection, the outer and inner surfaces of `the Washer being tangent respectively to the curvatures of the outer and inner surfaces of the shoe.

l0. A shoe for the field of a dynamo electric machine, consisting of heavy rolled sheet metal formed to the curvature of the armature and having a perforation through which a core piece may be riveted and partially extruded around said perforation to form a Washer-like projection having substantially equal area outer and inner flat surfaces defined by substantially equal diameter outer and inner Walls.

ll. shoe for the field of adynamo electric machine, consisting of heavy rolled sheet metal formed to the curvature of the armature and having a perforation through Which a core pice may be riveted and partially extruded around said perforation to form a Washer-like projection having substantially equal area outer and inner flat surfaces defined by substantially equal diameter outer and inner Walls, the outer and inner surfaces of the Washer being tangent respectively to the curvatures of the outer and inner surfaces of the shoe.

Signed at Bayonne, in the county of Essex and State of New Jersey, this 5th day of March A. D. i922.

HARRY C. GRANT. 

